Research Of Movement Rules About Particles For The Inclined Medium-thick Ore Body

For exploiting the inclined medium-thick ore body with sublevel caving method,a higher ore loss and dilution generally exists in practical because of the direct contact between blasted ore and overlying waste rock and the complex granular flow mechanism.So the research on movement laws about particles for the inclined medium-thick ore body has a significant effect on decreasing the high ore loss and dilution rates and providing a theoretical basis and guidance for actual production.Therefore,taken the extraction of inclined medium-thick ore body with sublevel caving as the research object,the laboratory scaled physical model draw experiments,theoretical analysis and numerical simulation experiments were carried out considering mainly the influence of the thickness and angle of the ore body on the gravity flow of particles under the inclined wall condition.The main research work is as follows.(1)A scaled physical draw model with a geometrical scale of 1:25 was deigned to carry out the draw experiments.Based on the physical experimental results,the primary characteristics of the granular flow axis were analyzed.The granular flow axis could be divided into two parts.One was called the upper flow axis,which was approximately parallel to the inclined upper boundary.The other part was defined as the lower flow axis that coincided with the central axis of the draw point.As the thickness or angle of ore body changed,the length of upper and lower flow axis changed correspondingly.(2)A new thought,which was the granular flow area could be simply divided into two parts,was proposed according to the demarcation point of flow axis.The two parts were the area uncontrolled by the inclined wall(i.e.the free fall area)and the area controlled by the inclined wall,respectively.The upper inclined wall had a slightly effect on the draw body's shape which was an approximate truncated ellipse in the uncontrolled area.However,in the area affected by the upper wall,the shape of draw body,which was a regular ellipse no longer,produced a variation and rotation to a certain extent.When the heights of draw were equal,the angle and thickness of ore body had a significant influence on the mass drawn.(3)For exploiting the inclined medium-thick ore body with sublevel caving method,the residual loss of ore,which could be influenced by the thickness and angle of ore body,mainly existed on the lower wall.The boundary of the residual ore on the lower wall was approximately parallel to the inclined upper wall.Moreover,the lower part of the boundary of the residual ore was funnel-shaped.(4)On the basis of the simplified granular flow area and the stochastic medium draw theory,a theoretical research of the gravity flow of the above two areas was conducted.The equations,particle movement velocity,particle movement trace,drawn-funnel and the shape of draw body,were deduced and established based on the probability density function of granular particle movement.Made a comparison of experimental and theoretical shape of draw body,it was confirmed that the two coincided with each other basically so that the reliability of movement equations of particles deduced was validated.(5)The ore body with the dip of 45° and the thickness of 10 m was taken as an example,the simulation experiment that researched the gravity flow was conducted with the two-dimensional particle flow numerical simulation software.During the process of ore drawing,particles flowed to the free fall area quickly in the form of similar line along the upper wall,approximately,and then flow in the vertical direction into the upper area of the draw point.However,the particles,which were close to the lower wall,moved slowly because of the accumulation effect as the result of the inclined angle.The characteristic,which was the state of particles reached equilibrium and then destroyed was cyclic and repeating in the process of ore drawing,made the force curves of upper and lower wall that generated by the motion of particles display in the form of increasing and decreasing suddenly.